Question

I am using the following SQL in my stored procedure to not filter by date parameters if they are null.

WHERE (Allocated >= ISNULL(@allocatedStartDate, '01/01/1900') 
       AND Allocated <= ISNULL(@allocatedEndDate,'01/01/3000'))
AND
(MatterOpened >= ISNULL(@matterOpenedStartDate, '01/01/1900') 
 AND MatterOpened <= ISNULL(@matterOpenedEndDate, '01/01/3000'))

Will this give any kind of performance hit when dealing with a lot of records?

Is there a better way to do this?

Number of records – around 500k

Answer 1

Or just let the query optimizer have it:

WHERE ( @allocatedStartDate is NULL or Allocated >= allocatedStartDate ) and
   ( @allocatedEndDate is NULL or Allocated <= @allocatedEndDate ) and
   ( @matterOpenedStartDate is NULL or MatterOpened >= @matterOpenedStartDate ) and
   ( @matterOpenedEndDate is NULL or MatterOpened <= @matterOpenedEndDate )

Note that this is not logically equivalent to your query. The last line uses column MatterOpened, not Allocated, as I assume that was a typographic error.

If performance is really an issue, you may want to consider adding indexes and changing the stored procedure to execute different queries based on the parameters. At least break it into: no filter, filter only on Allocated, filter only on MatterOpened, filter on both columns.